Telephone system



Jan. 28, 1930. B. A. WAITLACE 1,744,345

TELEPHONE SYSTEM Original Filed Jan. 30, 1928 Patented Jan. 28, 1930 YSTATES-PATENT FECE ' BEE-T A. WALLACE, OF CHICAGO; ILLINOIS, ASSIGNOR TOKELLOGG SWITOHBOARD AND SUPPLY COMPANY, or CHICAGO, ILLINOIS, A.CORPORATION OF ILLINOIS- used. It has been the universal practice to VTELEPHONE SYSTEM Application filed January 30, 1928, Serial No. 250,466.Renewed June 27, 1929 My invention relates to code ringing apparatussuch as 1s used In connection with telephone systems to ringthedlfl'erent stations upon a poly-station line and has'to do moreparticularly with telephone systems of the type wherein so called coderinging is manually code ring the different substations upon apoly-station line, but the manual method, especially in the case of apoly-station line which may have as high as twelve substations connectedthereto, is slow and inaccurate for the reason that the different op-,erators diiferently transmit the same code ring which causes confusionand the giving of false code rings. To overcome this inaccuracy I havearranged a code ringing mechanism which automatically transmits the coderings accurately withno other duty necessary on the part of the operatorthan to select the required code and then press the ringing key; a

. The principal object of my invention is to provide a simple, compactand inexpensive device to automatically code ring the stations on apoly-station telephone line, and a further object of my invention is;the provision of means insuring the signaled station of,

the'reception of the full code ring, regardless of the-position in whichthe interrupter apparatus associated with the code ringing mechanism maybe at theftime the operator selects the desired code. 7 p

A stillfurtheri object ofImy invention is the provision of meansassociated with the code ringing mechanism which after one complete codering. is transmitted automatically cuts ofi the ringing code. Anotherfear iture is the provision of visual signal means associated with thecode ringing mechanism which notify the operator oi the completed ringso she may supervlse theconnection and in case another application oftheparticular ringing code is necessary to again signalthe calledforsubscriber sh'emay again start the code ring. A e V p The above featuresas well as others not specifically pointed out will be, described'in.detailin the ensuing specification and appended claims.

' Fora more complete understanding of my I invention reference may behad to the accompanying drawing in which I show the mechanical coderinging mechanism of my in- I vention associated with amagnetocordcircuit C for interconnecting magneto substations A and B whichterminaterespectively in line circuits L and L at the exchange and whichcomprise respectively combined visual signals or drops DS and DS andjacksJ and J, The magneto cord circuit C for interconnectingthe magnetosubstations A and B comprises answering and calling plugs AP and GP andthe usual clearing out drop signals OS and CS. A listening key LK isalso associated with the cord circuit C and when actuated connects theOperators set 0 to the cord conductors to enable the op erator toinquire the wants of the calling subscriber or for the purpose ofsupervising a connection. ringing key BK is also associated with thecord circuit C and when actuated operates meansassociated with theringing code mechanism to applying the particular code ring selected tothe called substation of a poly-station line such as that with which thesubstation Bis associated.-

The cord circuit C is oneof a plurality with which each position o f'anexchange switchboard is equipped as is well understood in the art andassociated with a master ringing key" .MK which 1s commonto the positionwith which the cord circuit C is associated. The

master. ringing keyMKcomprises twelve sets of springs 2 to 13 inclusivewhich are provided with push buttons for actuating the same. The springs2 to '13 inclusive and as- MK is conveniently locatedin each position 1of an exchange switchboard, and the spring I groups2 to 13 inclusivewhic'hcomprise the masterkey-MK are associated with twelve combinationsof codes, aswill be more fully hereinafter described. The ringing key RKassociated with the cord circuit C controls the operation of amastercontrol'relay MC and this master control relay MC in turn con- 7trols the operation of a group of code ring connecting relays CR, CR, CRand CR individual to the cord circuit C. The group of relays CR, CR, CRand CR are energized in various combinations depending upon which of thekeys 2 to 13 inclusive of the master ringing key MK is depressed toconnect a certain code ring to a called line as will be more fullyhereinafter described. A code ringing conditioning relay RCR, a ringin"guard relay GU, and a ringing cut off rei ay R0, a ringing guard lampsignal RG and ringing interrupter relay RI are also associated with thecord C and are for purposes as will presently be described.

A constantly rotating interrupter IN common to the exchange switchboardhas secured to its rotating shaft twelve disks 14 to inclusive each ofwhich is provided with a different number or combination of projections26 to control the different code rings. The character of the code ringis dependent upon which of the keys 2 to 13 inclusive is depressed andthe combination of relays CR, CR, CR and CR which are actuated due tothe actuation of a certain key of the master ringing key MK. A disk 27is provided on the interrupter shaft, which prevents the s litting up ofa code ring should a key associated with the master ringing key MK bedepressed after the code has been started, and a disk 28 is alsoprovided, which upon the completion of one complete code ring bringsabout the actuation of relay apparatus in the cord to automatically stopfurther a plication of the code ring.

Having described in general the ap aratus comprising my invention I willnow c escribe the circuit operation more in detail. The subscriber atthe substation A desiring a connection operates the hand generator atthe substation to operate the drop signal DS at the exchange to signalthe operator. The operator associated with the cord circuit C noting theactuated drop signal DS inserts the answering plug AP into the jack J ofthe calling line and then actuates the listening key LK to connect theoperators set 0 to the cord conductors and inquires the wants of thecalling subscriber at A. The insertion of the plug AP into the jack Jrestores the drop signal DS and disconnects it from the line conductors.

Assuming that it is the subscriber at the substation B that is wantedthe operator inserts the calling plug CP into the jack J of the wantedline, and assuming further that the character of the code ring to signalthe subscriber at substation B is one long, one short and one long ring,the operator depresses the key 13 which is associated with this codering as will be more fully hereinafter described to close its contacts52, 53 and 54, and the operator after depressing the same holds it inits depressed position momentarily to maintain contacts 52, 53, and 54in their actuated positions. The operator having depressed key 13 of themaster ringing key MK now actuates the ringing key RK of the cord C andholds the same in its actuated position momentarily to start the codering to signal the called for substation B. The ringing key RK is of thenon-locking type as are also the individual keys 2, 3, 4 etc. of themaster key MK and after the respective keys 13 and RK have beendepressed they are held momentarily in their operated positions tocondition apparatus associated with the cord circuit C, the operation ofwhich will now be described. The closing of alternate contact 30 of thekey RK closes an energizing circuit for the master control relay MCtraced from battery through the winding of relay MC, conductor 31, toground at alternate contact 30 of the key RK and the relay MO is heldenergized as long as the key RK remains in its actuated position. Theclosing of alternate contact 32 of the ringing key RK closes anenergizing circuit for the code ring conditioning relay ROB traced frombattery through the upper winding 33 of the relay RCR, conductor 34,alternate contact 32 of key RK, conductor 35 to ground at normal contact36 of the emergency ringing key EK. The relay RCR energizing closes itsalternate contacts 37, 38, 39, 40 and 41 and the closing of itsalternate contact 38 establishes a locking circuit for itself tracedfrom battery through the upper winding of relay RCR, alternate contact38, conductor 42 to ground at normal contact 43 of the listening key LK.Should the listening key LK be in its actuated position at the time therelay RCR is initially energized the locking circuit of the relay RCRwill extend from battery through the lower winding 44 of relay RCR, itsalternate contact 39, conductor 45 to ground at normal contact 46 of theringing cut off relay R0, but with the listening key LK in its normalposition locking circuits are established through both winding 33 and 44as just described.

The master control relay MC having been energized as just describedcloses its alternate contacts 47, 48, 49, 50 and 51 and having assumedthat the key 13 of the master ringing key MK is associated with the codering signalling the called for substation B, the closing of alternatecontacts 52, 53 and 54, of the key 13 close energizing circuits forcertain of the group of four code ring connecting relays CR, CR, CR andCR The closing of alternate contact 52 of the key 13 establishes acircuit for relay CR- traced from battery through the lower winding 55of relay CR, conductor 56, alternate contact 47 of relay MC, conductor57 to ground at alternate contact 52 of the key 13. The relay CRenergizing closes its alternate contacts 58, 59,60, 61 and 62 and theclosing of its alternate contact 58 establishes a locking circuit foritself traced from battery through its upperwind-i ing 63, its alternatecontact 58 I and conductor to ground at normal contact 46 oi the re layR0 'The closingot alternate contact 53 of the key '13 closes anenergizing circuit for the relay CR of the groupof code ring concontact54 of the key 13 closes an energizing circuit for the code ring[connecting relay CR traced from; battery through thelower Winding 710irelay GRflconductor 72, alternate contact of relay MG, conductor 73 toground at alternate contact 54 of the key 13, e

and the relay QR energizing closes its alternate contacts 74 and 75; Theclosing of alternate contact 74 of relay CR establishes a lockingcircuit for relay CR? trace'dfrom bat tery through its u per inding 76,itsalter nate contact 7 4 and conductor 45 to ground at normal contact46 offre;layRO. The relays CR, CR and CR having been energized and.locked up due to the momentary depression of the key 13 of the masterkey group MK and the ringing key RK of'the cord circuit C --having beenactuated momentarily to cause the ene'rgization and locking up of relayRCR, the release of the ringing key RK permitsthe relay MC toqrestoreTherestoration ofrelay does not affect the relays CR, CB and CR as theyare locked up to ground at normal contact 46 of relay R0 and relay ROBis not efiectedby the restoration of the key RK because relay RCReislockedup to ground at normal contact 43 of the ringing key LK and therestoration of the kev 13 of the master key MK allows contacts 5 5 and54 to assume theirenormal position. v lVith the relays CR, CR Vand CRand relay BUR energized I will now describe how the vcode ring isapplied to the called substation B. f ofpthe. cdnnected plug GP and a ckthmugrhp.

the call bell at-the called substation B, back through the sleeve"contacts of the connected"- Assumingv that the interrupter IN which isconstantly rotating is in the position 'illustrated Whenthe key 13 andthe ringing'key' RK Were depressed, the disk 27 rota-ting causes theprojection 88 0n the said disk 27 to move the spring 89 into engagementwith the spring 90 to close anenergizing circuit for the ringing guardrelay GU traced from battery through the lowervvinding-9l of relay GU,-conductor 92, normal contact 93 of relay 7 R0, conductor94,alternate'contact 41 of relay RCR, conductor 95 to ground through closedcontacts 89and 90 The relayGU' energizing, closes its alternate contacts96, and 98 and the closing oflits alternate contact 96" establishes: alookingfeirouitfor relay GU traced from battery thrcmgh'theupper'winding 99 of relay GU, its alternatecontact'96 and conductor 45to; ground at n-orinalcontact 46 of relay R0" The master ringing key MKis provided With twelve groups of springs. 2 to 13 inclusive which Whenthe keysare depressed for code ringing move-to their alternatepositionsxto, bring about the operation of certain combinations of thegroup of code ring connecting relays CR; GR", CR and CR There are asmanydisks 14, 15 etc. provided with projections 26 as there are keysassociated With the master ringingkey MK andithese disks 14, 15 etc; areprovidedrwi-th different combinations of projections 26 to control thecode ringing; 1 The group of relays CR, CR etc; are ener 'gize'd invarious combinations depending upon which of the keys 2 to 13 inclusiveis depressed and each combination of energized;

relays OR, OR, etc. thus associates a 'certain' disk of the interrupterIN to apply-a pre'- determined code ring to a called line. a

One long,- one short and one long ring is* the code ring forsignally thecalled substa-t ti-on B and the operationof therelays CR-, CR and CRWhen the key 13 of the master ringing key MK is depressed,- associatethe disk 14 with the called line and as the interrupter IN continuesto-rotate the first pro-'1 jection '26- on the disk l4engages the spring100 and moves it into engagement with the contactlOl, closing anenergizing circuit for the ringing interrupter relay Rltraced fromenergized, conductor 106, alternate contact 59 of'relay GR,conduotor-107to ground through closed contacts 100 and 101. Therelay RIenergizing closes its alternate con tact 108 to connect the ringinggenerator G to the called line B, the ringing circuit being traced fromthegenerato'rG through alter nate contact 1-08 of relay R1, the tipcontacts jack J and plug GP to ground at alternate nate contaet110= frelay Rlto the tip conductor of the cord 0 to give the calling sub:

scriberat substation A an audible ringing Signal as is wellunderstood, W

When the first projection 26' of the disk 14' disengages thespring 100the said spring 100 moves to its normal position and 'disengage's thespring-101'and this"interruptionof rhe contacts 100 and 101 opens theenergizing circuit of the ringing interrupter relay RI. Vhen the secondand third projections 26 and 26 respectively engage the spring 100 tomove the same into engagement with the spring 101 two more energizationsand deenergizations of the relay RI are brought about to transmit twoadditional impulses of ringing current to the call bell at thesubstation B. Thus one long, one short and One long ring which we haveassumed is the code ring of the called substation B are transmitted tothe called substation 13. Just before the completion of one revolutionof the interrupter shaft upon which the disks are mounted, a projection113 on the disk 28 engages a spring 114 and moves the same intoengagement with a contact 115 which closes an energizing circuit for theringing cut off relay RO traced from battery through the upper winding116 of relay BO, conductor 117,

alternate contact 97 of relay GU, conductor 118, alternate contact 40 ofrelay RCR, conductor 119 to ground through closed contacts 114 and 115.The relay BO energizing closes a locking circuit for itself traced frombattery through its lower winding 120, its alternate contact 121,conductor 34, alternate contact 38 of relay RCR and over conductor 42 toground at normal contact 43 of the listening key LK. The opening ofnormal contact 46 of relay RO opens the locking circuit of relay GUwhich restores to normal and the opening of its alternate contact 97opens the initial energizing circuit for relay RO but as a lockingcircuit has been closed through its lower winding as just described, thesaid relay RO remains energized. The opening of contact 46 of relay GUalso opens the locking circuit of relay RCR which extends through itslower winding 44 but the locking circuit through its upper winding 33maintains the relay RCR energized to ground at normal contact 43 of thelistening key LK. The opening of normal contact 46 of relay RO opens thelocking circuits of the relays CR, CR and CR and these relays nowrestore to normal. The closing of alternate contact 46 of relay BOestablishes a circuit for the ringing guard lamp HG, traced from batterythrough the lamp RG, alternate contact 37 of relay BUR, conductor 123 toground at alternate contact 46 of relay R0. The lamp RG is lighted overthis circuit and gives the operator an indication that one complete codering has been transmitted. The operator now supervises the connection byactuating the listening key LK to connect the head set 0 to the cordconductors. The listening key LK when actuated opens its normal contact43 which interrupts the locking circuits of the relays R0 and RCR andthe said relays now restore to normal. If the called subscriber atsubstation B has not as yet answered the operator will restore herlistening key LK and again operate the key 13 and actuate the ringingkey RK of the cord circuit C to again complete the cycle of operation asbefore described. The subscriber at B in response to the signal removeshis receiver and the talking circuit may now be traced over the heavilymarked conductors. The subscribers at the respective substations A and Bu on the termination of their conversation rep ace their receivers upontheir respective switchhooks and then actuate the hand generators tooperate the clearing out signals CS and CS. The operator noting the twoactuated drop signals CS and CS knows that the conversation hasterminated and removes the plugs AP and GP from their respective jacks Jand J and also restores the clearing out signals CS and CS.

The disk 27 with its projection 88 acts as a guard against the splittingup of the difierent code rings and assuming that the operator hasdepressed the key 13 after the projection 88 on the disk 27 has passedthe spring 89, no energization of the relay GU is brought about, as theenergization of the relay GU is controlled by the contacts 89 and 90.The relay GU remaining at normal its alternate contact 98 remains openand no impulses of current are extended to the interrupter relay RI andtherefore no ringing current is transmitted to the called line until thedisk has completed a revolution. When the projection 88 again engagesthe spring 89 it is again moved into engagement with contact 90 to bringabout the energization of relay GU and the closing of its alternatecontact 98 will permit the ringing interrupter relay RI to be energizedand deenergized to connect and disconnect the generator G to the calledline to signal the called subscriber by the selected code ring.

Assuming that the key 12 of the master key MK is depressed thesprings'130, 131 and 132 are moved to their alternate positions to closeenergizing circuits for certain of the relays of the group of relays CR,CR, CR and OR. The closing of contact 130 of the key 12 closes a circuitfor relay CR extending from battery through the winding 82 of relay CR',conductor 83, alternate contact 48 of relay MR (which is energized whenthe ringing key RK of the cord C is actuated as before described),conductor 84 to ground at alternate contact 130 of the key 12. Relay GRis locked up through its winding 85, its alternate contact 77 to groundat normal contact 46 of relay R0. The closing of contacts 131 and 132 ofthe key 12 connect ground through the respective windings 64 and 71 ofrelays CR and CR to energize the same and the locking circuits of therelays CR and CR are the same as previously described and thiscombination of operated relays CR, CR and CR associates the interrupterdisk 22 with this combination which provides two long impulse of currentreceived by the relayQRI will be when'the first projection 26 engagesthe spring 133 to move it into engagement with the spring 134 and thisimpulse extends from ground through the closed contact springs 133 and134' associated with'the disk 22, conductor 135, alternate contacts 78,68 and 75 of relays CRQCR and CR and over the previously described pathof the relay RI and battery. The operation of the circuit from thispoint o'n is the same as previously described and further description isnot thought necessary; i I Referring again to the combination of relaysCR, CR and CR which wereenergize'd when'the key 13of the master keygroupMK was depressed, I will now point outhow only this selected codering is impressed on the called line. The disk 15 rotating causes theprojections thereon to close its associated 7 spring contacts but'theseclosures are only incidental and the conductor 140 extending from theclosed spring contacts isnot cut through. as normal contact 59 of relayOR is open. The disk 16 also closes its associated contacts but theconductor 141 extending from the closed spring contacts is not cutthrough as normal contact 68 of relay CR is open; the disk 17 closes itsassociated contacts but without effect. as the conductor 142 extendingfrom the closed spring contacts is not cut through as normal contact60015 relay CE is open; the disk 18 closes its associated contacts butwithout eflect as the cone ductor 143 extending from the close'dspringcontacts is not cut through as normal contact 7 5 of relay CR is openthe disk 19 closes its associated contacts but without effect as theconductor 144 extending from the closed spring contacts is not cutthrough as normal i contact 61 of relay is open; the disk 20 closes itsassociated contacts but Without effect as the conductor 145 extendingfrom the closed spring contacts is not cut through as normal contact 69ofrelayCR is open and the disk21 closes its associated spring contactsbut without effect as the conductor 146 extending from the closed springcontacts is not cut through as normal'contact 62 0f relay GR is open.The disks 22, 23, 24 and 25 close their associated contacts but withouteflect as the conductors 135, 147, 148 and 149 ex- 1 tending'from theclosed contact springs of the respective disks 22, 23, 24 and25 are notout through as the relay GR is not energized and its alternate 4contacts 78, remain open.

From the foregoing description it is readily apparent that the code rng-mg 1s non-inter- 79, and 81 fering and that each combination, ofenergized relays of the group of relays CR, CR

etc, connects on'lythe interrupter disk associated with the energizedcombination to connect the said diskwith'the interrupter relay Blandthis disk is the one that delivers the code .ring associated". with thekey of the master ringing key. MK that is depressed.

It. is also apparent thata plurality of keys maybe depressed forextending ringing current from the cord. circuits with whichthe masterkey groupMK is common Without interfering with each other.

I also provide an emergency ringing ke EK which may be used by theoperator of the cord circuit C to send a special code ring manually to acalled line or for ringing an individualline; The key EICmay also beused for. code ringing the subscribers on a poly-station line should themechanical code ringing equipment be out of order. To use the key EK tomanually'ring asubscriber on a poly-station linethe said key EK is actuated -to close its'alternate contact 150 and the ringing key RK of thecord C is moved to its alternate position to close its alternatecontacts 30 and 3 2. The closing of contact 32 of the key RK is onlyincidental but the closing of alternate contact 30 of the keyRK closesan energizing circuit for the master control relay MC over a pathpreviously described. The relay MC energizing its alternateco-ntact 51is closed and as the key EK has been moved to its actuated position andheld in that po'sition an energizing circuit for the ringing interrupterrelay BI is esta'blished from battery through the winding of relay RI,conduct0r1Q2,alternatecontact 51 of relay MC, conductor 151 to ground atal ternate contact 150 of the key The relay RI energizing closesitsalternate contact 108 to connect the ringing generator G to thetipconductor of the cord- C and with the calling plug OP in the'jack of-acalled line ringing current is transmitted to operate the call bell atthe calleds'ubstation'l The key EK may be operated to energize anddeenergize the relay BI any number of times to transmit code ringing asis well understood. 7

While I have illustrated and described my invention with a particularform of cord circuit it isappare'nt that other forms of cord circuitmaybe used and that many changes and modifications may be made in theapparatu's without departing from the spirit and scope of the same. Y IHaving described my invention what I claim is newfand desire to securebyUnited States Letters Patent is:

cuit for connection to said line, codefringin'g apparatus associatedwith saidlink circuit,

a master key associated with said link circuit comprising a plurality ofkeys for individu-j ally associating the different codes with said linkcircuit, a ringing key and a group of j relays for said link circuit,and means responsive to an operation of said ringing key to associate adepressed key of said master key with said group of relays whereby acertain combination of said group of relays are responsive to connectthe desired code ring to a substation on said poly-station line.

2. A telephone system including a polystat-ion telephone line, aconnecting link circuit for connection to said line, code ringingapparatus associated with said link circuit, a master key associatedwith said link circuit comprising a plurality of keys for individuallyassociating the different codes with said link circuit, a ringing keyand a group of relays for said link circuit, means responsive to anoperation of said ringing key to associate a depressed key of saidmaster key with said group of relays whereby a certain combination ofsaid group of relays are responsive to connect the desired code ring toa substation on said poly-station line, and means associated with saidcode ringing apparatus for disconnecting said code ringing from saidconnected line after one complete code ring has been transmitted.

3. A telephone system including a poly station telephone line, aconnecting link circuit for connection to said line, code ringingapparatus associated with said link circuit, a pluralit of keysassociated with said link circuit or individually connecting thedilierent codes to said link circuit, a ringing key and a group ofrelays for said link circuit, means responsive to an operation of saidrin ing key to associate a depressed key with sai group of relayswhereby a certain combination of said grou of relays are responsive toconnect the desired code ring to a substation on said poly-station line,and means associated with said code ringing apparatus for insuring thatany substation upon said line will receive a full code ring.

4. A telephone system including a polystation telephone line, aconnecting link circuit for connection to said line, code ringing aparatus associated with said link circuit, a p urality of keysassociated with said link circuit for individually connecting thedifferent codes to said link circuit, a ringing key and a group ofrelays for said link circuit, means responsive to an operation of saidringing key to associate a depressed key with said group of relayswhereby a certain combination of said group of relays are responsive toconnect the desired code ring to a substation on said poly-station line,and means associated with said code ringing apparatus controlling relaymeans in said link circuit for insuring that any substation upon saidpoly-station line will receive a full code ring.

5. A telephone system including a polystation telephone line, a linkcircuit for connection therewith, code ringing apparatus, manuallycontrolled springs, a group of selecting relays controlled by saidmanually controlled springs to select the desired combination of saidrelays to associate the said code ringing apparatus with said line topermit the application of the necessary code to said line to ring thepredetermined substation thereon, and means associated with said coderinging apparatus for disconnecting the said code ring from said lineafter one complete ring has been transmitted.

6. A telephone system including a polystation telephone line, a linkcircuit for connection to said line, code ringing apparatus, selectingrelays, manually controlled selecting apparatus for controlling saidrelays, means controlled by said relays for applying a ringing code fromsaid link circuit to said telephone line to signal a desired substationon said line, and means associated with said ringing code fordisconnecting the code ring from said line after one complete ringingcode has been transmitted.

7 A telephone system including a polystation telephone line, aconnecting link circuit for connection to said line, code ringingapparatus associated with said link circuit, a plurality of keysassociated with said link circuit for individually connecting thedifferent codes to said link circuit, a ringing key and a group ofrelays for said link circuit, means responsive to an operation of saidringing key to associate a depressed key with said group of relayswhereby a certain combination of said group of relays are responsive toconnect the desired code ring to a substation on said poly-station line,and means associated with said code ringing apparatus controlling relaymeans in said link circuit for disconnecting said impressed code ringfrom said connected line after one complete code ring has beentransmitted.

8. A telephone system including a poly-station telephone line, aconnecting link circuit for connection to said line, a ringing currentenerator, a relay for connecting said ringlng current generator to saidline, code ringing apparatus associated with said link circuitcomprising a plurality of keys for individually associating thedifferent codes with said relay, a ringing key and a group of relays forsaid link circuit, and means responsive to an operation of said ringingkey to associate a depressed key with said group of relays whereby acertain combination of said group of relays are responsive to connectthe desired code with said relay to energize said relay according to thesaid desired code to connect said generator current to a substation onsaid poly-station line.

9. A telephone system including a polystation telephone line, aconnecting link circuit for connection to said line, a ringing currentgenerator, a relay in said link circuit for connecting said ringingcurrent generator to said line, code ringing apparatus associated withsaidlink circuit comprising a plurality of keys for individuallyassociating the different codes with said relay, a ringing key and agroup of relays for said link circuit, and means responsive to anoperation of said ringing keyto associate a depressed key with saidgroup of relays whereby a certain combination of said group of relaysare re sponsive to connect the selected code With said relay to energizethe same according to the said selected code to connect the saidgenerator ringing current to a particular substation on saidpoly-station line and means in said link circuit for disconnecting saidconnectedcode from said relay after one complete code ring has beentransmitted.

10. A telephone system including a polystation telephone line, aconnecting link circuit for connection to said line, code ringingapparatus associated with said link circuit, a plurality of keysassociated with said link circuit for individually connecting thedifferent code interrupters associated with said keys to said linkcircuit, relay means and a ringing key for said link circuit, meansresponsive to an operation of said ringing key to associate a selectedkey with certain of said relay means which are responsive to connect acode interrupter associated with said selected key to means in said linkcircuit to operate said means according to the selected code to transmitthe code ring to a substation on said polystation line.

11. A telephone system including a polystation telephone line, codeinterrupter apparatus, a group of selecting relays, manually controlledmeans for actuating said relays to select the desired code to be appliedby said code interrupter apparatus, ringing means controlled by saidrelays for signaling the desired substation connected to said telephoneline, and means associated with said code interrupter for disconnectingthe same from said line after one complete ring hasbeen transmitted.

12. A telephone system including a polystation telephone line, a linkcircuit for connection therewith, code ringing apparatus, manuallycontrolled keys, a group of selecting relays controlled by said keys toselect the desired combination of said relays to associate the said coderinging apparatus with said line to permit the application of coderinging current to said lineand signalling means for said link circuitresponsve upon the termination of one complete application of said coderinging curren V 13. A telephone system including a poly stationtelephone line, a link circuit for connection therewith, code ringingapparatus, manually controlled springs, a group of selecting relayscontrolled by said manually controlled springs to select the desiredcombination of said relays to associate the said code ringing apparatuswith said line to permitthe application of the necessary code to'said lne to'ring the predetermined substation thereon, means associated withsaid code ringing apparatus for disconnecting the said codermg fromsaidline after one complete cringhasl been transmitted andlmeans forslgringing key to associate a depressed key with said group ofrelayswhereby a certain come bination of said group ofrelays are responsive toconnect the desired code ring to a substation on said polystation line,means associated with said'code ringing apparatus for insuring thetransmission of a full code'ring to said polystation lineand signallingmeans operable upon the completion of one full code ring to said line. iv

15. A telephone system including a polystation telephone line, a linkcircuit for connection to said-line, code ringing aparatus associatedwith said link circuit, a plurality of keys for individually connectingthe different codes to said link circuit, a ringing key and agroup ofrelays for said link circuit, means responsive to an operation of saidringing key to associate a depressed key with said group of relayswhereby a certain combination of relays are responsive to connect thedesired code ring to a sub-station on said polystation line, meansassociated with said code ringing apparatus for insuring the transmission or a full code ring to said polystation line, means fordisconnecting the said code ring from said line after one complete codering has been transmitted.

16. A telephone system including a polystation telephone line, a linkcircuit for connection to said line, code ringing apparatus associatedwith said link circuit, a plurality of keys for individually connectingthe different codes to said link circuit, a ringing key and a group ofrelays for said link circuit, means responsive to an operation of saidringing key to associate a depressed key with said group of relayswhereby a certain combination of relays are responsive to connect thedesired code ring to a substation on said polystation line, meansassociated with said code ringing apparatus for insuring thetransmission of a full code ring to said polystation line, means fordisconnecting the said code ring from said line after one complete ringhas been transmitted and signalling'means responsive to the operation ofsaid disconnectingmeans. 17. A telephone system including a polystationtelephone line, a link circuit for connection to said line, code ringingapparatus comprising a constantly rotating shaft, a plurality of diskssecured thereto, cams of different combinations secured'on said disks, aplurality of manually controlled keys, a ringing interrupter relayoperable to connect ringing current to said line, a ringing key and agroup of relays in said link circuit, means responsive to an operationof said ringing key to associate a depressed key with said group ofrelays whereby a certain combination of said relays operate and connectsaid ringing interrupter relay in a circuit controlled by a certain oneof said disks on said shaft.

18. A telephone system including a polystation telephone line, a linkcircuit for connection therewith, code interrupter apparatus, a group ofselecting relays, manually controlled means for actuating said relays toselect the desired code to be supplied by said code interrupterapparatus, ringing means controlled by said relays for signalling thedesired substation on said polystation line, means associated with saidcode interrupter for disconnecting the same from said line after onecomplete ring has been transmitted and means in said link circuitoperable upon 30 said disconnection to inform the operator of saiddisconnection.

Signed by me at Chicago, in the county of Cook and State of Illinois,this 26th day of January, A. D. 1928.

35 BERT A. WALLACE.

